Well ok- what exactly did you do? Settings- sequence frame rate in FCP, codec, export type. And what did you do in MPEG-Streamclip. I can assure you if done properly video looks great on Vimeo so somehow there's a mistake you've got in your workflow and the easiest way to get help is to describe all the details so we can help you figure out where the mistake is.
"File" > "Export..." > "QuickTime Movie" > Use the following settings...
Open MPEG Streamclip > "List" (drop down menu) > "Batch List" > "Add Files" > Navigate and add files > Use the following settings...
Select an output file name/folder > Use the following settings in the next window...
Click "Presets..." > Click "New" > Enter a name > Click "Save" (now you don't have to re-enter in your settings every time you want to export to Vimeo.)
Click "To Batch" > Click "Go"
You might need to edit a few of the settings I've used in my preset, such as "Deinterlace Video" if you're using interlaced footage, and if you're just wanting a quick export to show somebody a revision of an edit, you can uncheck Multipass, reduce the quality and enable DV-PAL/NTSC on the Frame Size instead, and use a bitrate of 2000-2500~.